A conductive ink is proposed that includes a metal powder such as a nickel powder and a platinum powder, and a metal oxide powder dispersed in a solvent, and that can thus be used to form wiring and electrodes by using techniques such as inkjet printing (see Patent Document 1). This type of conductive ink requires the metal powder and the metal oxide powder to be stably dispersed in the solvent to ensure desired conductivity for the conductor formed by printing.
In ink containing two or more kinds of solid particles such as metal particles and metal oxide particles, the particle surface properties are generally different for each different solid particle, and accordingly the type of dispersant appropriate for adsorption on the particle surface also differs for each type of solid particle. This makes it difficult to disperse two or more kinds of solid particles in the ink using a sole kind of dispersant.